1. Field of the Invention
The present invention relates to a dual-function padlock, and more particularly to a padlock which can be unlocked by numerals or a key and can be locked without the need to match correct numerals.
2. Description of the Prior Art
A U-shaped padlock is used to lock a luggage. In particular, a U-shaped numeral padlock is popular because it doesn't need a key, which is very convenient for travel. Nowadays, most countries are strict with travelers for the check of safety because of counter-strike and some countries require certified unlocking systems of padlocks, preventing the numeral padlock from being damaged. The certified padlock producers have to use common lock cores in the padlocks, so that the safety examiners can unlock a certified numeral padlock of a luggage by using a common key for examination.
A conventional U-shaped padlock, such as U.S. Pat. No. 5,715,709, only uses dials to unlock the padlock. The longitudinal axle of the shackle extends through the dials disposed in the dials channels of the lock body, so the rotatable cylinder provided on the axle of the shackle can be moved in and out of the alveolus at the central portion of the dials along with the axial movement of the axle of the shackle. A block is used to restrain the axle of the shackle from being out of the core hole of the lock body. In the axial movement space of the restrained axle of the shackle, the rotatable cylinder has an engaging tooth to be inserted in the alveolus at the central portion of the dials, and the core hole of the lock body has a tooth groove corresponding to the engaging tooth. The dials are turned to align the engaging tooth of the rotatable cylinder with the tooth groove, such that the engaging tooth can be moved in the tooth groove. After that, the axle of the shackle can be pulled outward and the hook end can disengage from the lock hole so as to unlock the padlock. When the numerals of the dials are not correct, the engaging tooth cannot be engaged in the tooth groove and the axle cannot be axially pulled to be in a locked status.
In fact, the conventional U-shaped key padlock and U-shaped numeral padlock are two different types of lock structures. It is somewhat difficult to combine the functions of the two padlocks. The simpler the structure is, the more difficult the technique is. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve this problem that the padlock requires numerals to unlock and that the padlock can be locked without the need of correct numerals.